Data source dependencies in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a data source in Terraform?

A data source lets Terraform fetch information from outside resources or existing infrastructure to use in your configuration.

beginner

Why do data source dependencies matter in Terraform?

Because Terraform needs to know the order to fetch data and create resources, dependencies ensure data sources are read before resources that use them.

intermediate

How does Terraform know the dependency order between data sources and resources?

Terraform automatically detects dependencies when a resource references a data source's attributes in its configuration.

intermediate

What happens if a resource uses a data source that depends on another resource?

Terraform creates a dependency chain, ensuring the first resource is created, then the data source reads updated info, then the dependent resource is created.

advanced

How can you manually add dependencies between data sources and resources in Terraform?

You can use the 'depends_on' argument in a resource or data source block to explicitly declare dependencies.

What does a Terraform data source do?

A Deletes resources

B Fetches existing infrastructure information

C Creates new cloud resources

D Runs scripts on servers

Data sources fetch information from existing infrastructure or external systems for use in Terraform.

How does Terraform detect dependencies between data sources and resources?

A By manual user input only

B By the order of blocks in the file

C By file name alphabetically

D By resource references to data source attributes

Terraform automatically detects dependencies when a resource references data source attributes.

Which argument can you use to explicitly declare dependencies in Terraform?

A depends_on

B depends

C require

D needs

'depends_on' is the correct argument to manually specify dependencies.

If a resource uses data from a data source that depends on another resource, what happens?

A Terraform creates resources in the correct order automatically

B Terraform creates all resources simultaneously

C Terraform throws an error

D Terraform ignores the dependency

Terraform builds a dependency chain and creates resources in the right order.

Can data sources create or modify infrastructure?

A Yes, they delete resources

B Yes, they create resources

C No, they only read existing data

D Yes, they modify resources

Data sources only read existing infrastructure information; they do not create or modify resources.

Explain how Terraform manages dependencies between data sources and resources.

Think about how Terraform knows what to create first.

Describe a scenario where you might need to use depends_on with a data source.

Consider when automatic detection is not enough.